Electrical transformer system



March 31, 1931'. w, GAY 1,798,874

ELECTRICAL TRANSFORMER SYSTEM Filed Nov. 9. 1929 Patented Mar. 31, 1931 UNITED STATES PATENT OFFICE FRAZER w. GAY, or NEWARK, NEW JERSEY ELECTRICAL TRANSFORMER SYSTEM Application filed Nov-ember 9, 1929. Serial No. 405,935.

This invention relates in general to elechours of the week, the load on the transformer trical transformer systems, one object of the system is between five and ten per cent of the invention being to provide a novel and immaximum. In office buildings the ratio of proved transformer system including means loaded to unloaded operation is about the for changing the magnetic density by a simsame. In factories lighting load is superim- 55 ple automatic switching operation and withposed on the daily load for about two hunout throwing the transformer or any of its dred hours per year, and this lighting load is windings out of the circuit. I about twenty-five per cent of the daily shop The character and objects of the invention operating load. In offices, this lighting load may be better understood by a consideration is often equal to one-half of the peak load. 60

of the fact that most transformer systems op- Transformers of known construction deerate for long periods of time at only light signed to produce a low core loss during the loads which are far less than the peak loads large portion of the year when the load is onewhich the system must be designed to carry. tenth or less of the maximum load, are very I The loads on such transformer systems may expensive and not generally used. The 65 vary from a maximum or peak of five huntransformers commonly used operate with dred thousand kilowatts (500,000 kw.) on one half per cent core loss and one per cent some days to a minimum of one hundred thoucopper loss. sand kilowatts (100,000 kw.) during nights, t is another object of my invention to pro the average load during the year being vide a novel and improved. transformer sys- 70 around two hundred fifty thousand kilowatts tem of the character described which shall be (250,000 kw.). capable of operating at light loads with an Assuming as indicated, that the system has extremely small core loss and shall cost less transformers to carry approximately four than known types of transformers for similar million five hundred thousand kilovolt ampurposes. 75 peres (4,500,000 kva.), the system will draw Other objects are to provide such a trans continuously approximately fifteen thousand former system including a novel arrangement kilowatts (15,000 kw.) in core losses. Durof transformer windings on the cores, and ing minimum load periods, the transformer simple and inexpensive switch mechanism,

core losses constitute a very appreciable part whereby a number of windings canbe oporso of the load, and it is evident that any system ated in series, for example under light load, that will greatly reduce these light load core or in parallel, for example under heavy loads, losses, will produce substantial economies in or as desired; to provide a transformer systhe operation of the system. tem of this characterhaving a plurality of While the power lost by the large public high tension coils and a similar number of low utility companies in transformer core losses is tension coils all solidly connected in circuit,

a large item, during light load periods the and switch means, whereby said coils shall be cost of such incremental power is only a small connected either in series or in multiple withfraction of a cent. However, there are many out throwing any of said coils out of circuit,

40 industrial companies where losses per kva. of and to obtain other advantages and results installed capacity are much greater, and the as will be brought out by the following de cost of incremental power to such companies scription. is generally from five to ten times the cost of For the purpose of illustrating the princian equal amount of power to a large utility ples of my invention I have shown it in the ac- 45 company. companying drawings embodied in a distri- Industrial plants usually operate, with bution transformer system which is supplied holidays and other shut downs excluded, from the source with a voltage of four thousabout forty three hours out of a total of one and one-hunderd fifty volts and steps down hundred sixty-eight hours per Week. Durthe voltage to two hundred forty volts.

59 ing the remaining one hundred twenty-five Referring to said drawings in which corerate at very low flux density,

number of turns, the voltages thereon will tank with the transformer T and havii a magnetic core transroriner T high tension criprimary coils l and 2 low tension or "secondary coils and l wound on the-same core.

The high tension coils have the respective terminals 26, 2?,and28, 29 andare conne d in series with the*hightensionorpriniarytcil 5 of the other transformer l which has terininals o'afnd lll. The lowtension coils 3 and 4 of the transformer have "the respective term'inals82, and 3%, 85'and connected in'series with {the secondary low tension coils 6 and 7 ot the'translormer T Thee coils Sand Thav'e a commonmid-connection 8 and the respectiye'endterminals and fil. Tl ese coils 6 and 7 also have an equal nuncer of turns, and are essentially one winding. In many cases the mid-tap Sis not necessary, lorexample, where it is desired to have'only one secondary voltage, for example 240 volts, instead'of two voltages; 24-0 v. and 120 v. shown.

In accordance with the invention, both transformers T and T are'deigned to opnd are so designedthat with the'coils connected in se- 'ries,=the'co-reswill not become saturated until "the voltage across the windings has been in creased more thantl ree times the normal voltage. This isdistinguished from the lZHOWD modern high efficiency low core loss iformers which are designed to operate 21. flH'X density such that the core will not hecome'saturatedup to twice the normal voltage impressed on their windings.

Due to the tact that el tensiontra slo'rmer coils 1 and 2 have an equal number of turns on a common core, the voltage of these coils willalways be substantiallyequal, and as the cells 3 and l also have an'eqi "always be substantiallyequal. This is a o stantiall-y equal voltages will be induced in each coil. t should he understood that it the coils 1 and 2 are wound uniformly on the core 50 then the'coils 3 and 4 will each be wound uniformly on the care 50 so that either 7 low tension coil 8 or lmay operate separately with both high tension coils 1 and 2; in the same manner the coils 6 and 7 willbe wound each to have a minimum impedance when operating separately with the primary coil 5.

The coils 1 and 2 have-the respective leads 13 and 1a which are connected to the primary leadsl9 and 20 over which the current is received at a voltage of four thousand one hundred fifty volts (4,150 y.) and the coils 6 and '7 have the respective leads 11 and 12 which are connected to the secondary lines and 9 across which the voltage is two hundred forty volts (2&0 v.). Automatic switches 15 and'22are providedi or opening and closing the respectiveleads 13, 1d and 11, 12, and theseswitches are shown as having operating solenoids 16 and 23 connected in series with the low tension distribution :line9. Thesole- 'noids cooperate with the cores 17 and 24 and the switches are normally infiue'ncedinto open position by the respective adjustable springs 21 and 25 which maybe-adjusted to cause the switches 15 and 22'to open-and close with approximately one-third "load on the distribution line 9. It should 'be understood that the closingo't the switches 15 an'd22'may be a coinplished-hy the use'oi current transformers in either the primary or secondary power leads, with the secondaries of the transformers actuating the switches. Thus there are two magnetic ci-rcuit's, one includ the primary coils 1 and 2"a nd their-retive secondary coils 3 and '4, and the spe ary coils 5, 7.

In operation of the system, when it is-ca-i r yinga light load, the switches 15'and-22 are open so as to lea-ve'the'coils ofthe transformers connectedin series as above'des'cribed and as shown in the simplified wiring diagram,

From a study of Figures2 and '3 it will he observed that at the ins'tantof switching of the windings from series to multiple, the windings l, 2, 3 and 4onthe core 'have ea er-including the primary coil-5 and second their voltage increased three times,"but the I polarity remains the same. hand all ofthe windings on the core- 51 have their Voltage increased three times, but their polarity is re versed. Upon a iall-ingoli olthe load to less than one-third of the maximum load on the dine -9, the solenoids are partially deenergized so that the spring-s21 Whilethe greatest economy may'general ly 1 On the other i be obtained when my invention is utilized in connection with transformers for lighting systems, the savings in connection with an industrial plant over the known types of transformer systems by my invention are considerable. Furthermore, the cost of my transformer system is less than the cost of known types of systems.

Some efforts have been made heretofore to accomplish aresult somewhat similar to that obtained by my invention by using two banks of transformers, a small capacity bank operating its core at a very low density and having a high light load efliciency, and another bank of about twice this capacity operating with a high core loss and relatively low copper loss. In such a system, the large transformer is switched on and off as the load varies, and in addition to an interruption of the circuit, the switches must have exactly the same capacity and insulation as used in my system; the switches must rupture against full voltage, i, e. they must have full voltage across them when open, while the switches in my system have only twothird voltage across them when open; if the small low core loss transformer of the old system is to operate at as low a core loss as the transformer of my system, the size and cost of the transformer will be substantially the same as the cost of the entire transformer equipment required in my system; and, the large capacity transformer of the old system, if operated at as high a density as is utilized in my system, will be substantially two-thirds as large as the entire transformer equipment used in my system.

It will be manifest to those skilled in the art, that by my invention it is possible to obtain a safer installation with approximately three-fifths of the transformer capacity neces sary in heretofore known systems, which is due to the fact that in my system substantially all of the transformer equipment is always used in the most economical manner.

lVhile I have schematically shown the preferred embodiment of my invention, it should be understood that this is primarily for illustrating the principles of the invention, and that the invention may be embodied in many different types of apparatus, and other modifications and changes may be made by those skilled in the art without departing from the spirit or scope of the invention.

Having thus described my invention, what I claim is 1. A transformer system including a plurality of high tension windings solidly connected together in circuit, a corresponding number of low tension windings solidly con nected together in circuit, circuit connections and switch means for throwing said windings from series circuit into multiple circuit when the switch means is respectively open and closed, and means cooperating with said switch means for closing the latter at heavy load and opening it at light load.

2. A transformer system including a trans former having a core and a pair of high tension windings and a pair of low tension windings thereon, a second transformer having a core and a high tension winding connected solidly in circuit with the high tension windings of-the first transformer and a low tension winding having a mid-tap and connected solidly in circuit with the low tension windings on the first transformer, and circuit connections and switch mechanism for throwing all said high tension windings and all said low tension windings respectively from series circuit into multiple circuit.

8. A transformer system including a transformer having a core and a pair of high tension windings and a pair of low tension windings thereon, a second transformer having a core and a high tension winding connected solidly in circuit with the high tension windings of the first transformer and a low tension winding having a mid-tap and connected solidly in circuit with the low tension Windings on the first transformer, and circuit connections and switch mechanism for throwing all said high tension windings and all said low tension windings respectively from series circuit into multiple circuit when said switch mechanism is respectively opened and closed, and means controlled by the load upon the secondary leads for closing the switch mechanism at heavy load and opening it at light load.

4. A transformer system including a trans former having a core and a pair of high tension windings and a pair of low tension windings thereon, a second transformer having a core and a high tension winding connected solidly in circuit with the high tension windings of the first transformer and a low tension winding having a mid-tap and connected solidly in circuit with the low tension windings on the first transformer, and circuit connections and switch mechanism for throwing all said high tension windings and all said low tension windings respectively from series circuit into multiple circuit when said switch mechanism is respectively opened and closed, electromagnetic means controlled by the current in the secondary leads, and means cooperating therewith for closing and opening the switch at a predetermined load upon an increase or decrease respectively in the load.

5. A transformer system including a transformer having a core and a pair of high tension windings and a pair of low tension windings thereon, a second transformer having a core and a high tension winding connected solidly in circuit with the high tension windings of the first transformer and a low tension winding connected solidly in circuit with the low tension windings on the first transformer, and circuit connections and switch mechanism for throwing all said high tension windings and all said low tension windings respectively from series "circuit into multiple circuit.

6. A transformer system including'atransformer liaving 'a 'core and a pair of high tension windings and a pair of low tension windings thereon, a second transformer having a coreand a high tension "winding connected solidly in circuit with the high tension winding ofthefirst transformer and a low tension winding'connected solidly in circuit with the low tension windings on the first transformer, andycircuit connections and switch mechanism for throwing all said high tension windings and all said low tension windings respectively fromseries'circuit into multiple-circuit when said switch'mechanism is respectively opened and closed, and means controlled by the load upon the low tension or secondary leads for closing the switch mechanism at heavy load and opening it at light-load.

7'. A transformer system including a'transformer having acoreand a pair of high tension windings'and atpair of low tension windings thereon, a second transformer having a core and a high tension winding connected solidly in circuit with the high tension windings of the first transformer and a low tension winding'connected solidly in circuit with the low'tension windings on the first transformer, and circuit connections and switch mechanismforthrowing all said :highatension windings and all said low tension windings respectively from series circuit into multiple circuit when said switchmechanism is'respectively opened and closed, electromagnetic means controlled by the current in the low tension or secondary leads, and means c0- operating therewith V for closing and opening the switch at a predetermined load uponan increase or decrease respectively in the load.

8. A transformer system including an odd number of primary coils for each phase permanently consecutively connected togethe'nxa corresponding number of secondary coils for each phase consecutively connected togethentwo magnetic'circuits ineach phase, alternate primary coils and corresponding alternate secondary coils being in one said magnetic circuit and the remaining coils being in the other said magnetic circuit, and-a switch mechanism in said circuits connected to change from series 'to parallel circuitall said primary coilsandall-said secondary coils on clos ng'of the switch mechanism.

9. .A transformer system includinganodd number of primary coils 'for each Fphase permanently consecutivelyconnected togethen a corresponding numoer of secondary-coils for cachzphase consecutively connected together, 'two ma'gnetic circuitsin eachphasa'alternate primary coils and corresponding alternate secondary coils 'being in one said magnetic messy;

circuit-and the remaining coils in -the-6ther said magnetic circuit, and a switch mechanism for cont-rolling said circuits so connected that, :upon closing, \the voltage across each coil 'is multiplied as :many times as there are primary-coils for each {Pb-3S8.

10. A trans former system including-an-odd number of primary coils for each phase permanently connected in consecutive arrangement and a corresponding odd number-of secondary coils for each phase similarly con nected, two magnetic circuits in each phase, alternate primary coils and corresponing alternate secondary coils=being in one said magnetic circuit and the remaining coils in the other said magnetic circuit, and a switch mechanism for controlling said circuits connected so that upon closing, the second-mentioned coils and the magnetic :flux interlacing saidcoils havetheinpolarity reversed.

FRAZER W. GAY. 

